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EP-2016-155

(Submitted on 25 Jun 2016)

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Abstract

The first full amplitude analysis of $B^+\to J/\psi \phi K^+$ with
$J/\psi\to\mu^+\mu^-$, $\phi\to K^+K^-$ decays is performed with a data sample
of 3 fb$^{-1}$ of $pp$ collision data collected at $\sqrt{s}=7$ and $8$ TeV
with the LHCb detector. The data cannot be described by a model that contains
only excited kaon states decaying into $\phi K^+$, and four $J/\psi\phi$
structures are observed, each with significance over $5$ standard deviations.
The quantum numbers of these structures are determined with significance of at
least $4$ standard deviations. The lightest has mass consistent with, but width
much larger than, previous measurements of the claimed $X(4140)$ state.

Masses of kaon excitations obtained in the default amplitude fit to the LHCb data,
shown as red points with statistical (thicker bars) and total (thinner bars) errors,
compared with the
predictions by Godfrey--Isgur [41] (horizontal black lines)
for the most likely spectroscopic interpretations
labeled with $n{}^{2S+1}L_J$ (see the text).
Experimentally established states are also shown
with narrower solid blue boxes extending
to $\pm1\sigma$ in mass and labeled with their PDG names [31].
Unconfirmed states are shown with dashed green boxes.
The long horizontal red lines indicate the $\phi K$ mass range probed in $B^+\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi K^+$ decays.
Decays of the $2{}^{3}{\rm P}_{0}$ state ($J^P=0^+$) to $\phi K^+$ are forbidden.